Any recommendations for something to protect against DDoS attacks, particularly those targeting DNS servers? I need something that is gigabit and preferably supports IPv6.

We currently have a pair of IPS/firewall devices that we really like and they do mitigate the attacks. But they are only 100Mb and we have been hit with floods of 400-800Mb that just overwhelm them, squashing all other traffic.

So we don't need some super duper all-in-one security appliance that will do everything including cook our breakfast for us. We just need to limit these high traffic bursts to a rate that our IPS devices can handle.